Downhole sand screen with automatic flushing system

Abstract

A pump that is configured to lift fluids through a tubing string includes a gas mitigation system and a screen flush module. The gas mitigation system has a canister with an interior and an intake screen. The gas mitigation system further includes an intake tube that extends into the canister. The screen flush module is configured to flush solids particles trapped in the intake screen.

What is claimed is: 
     
       1. An electric submersible pump configured to lift fluids through a tubing string contained in a well having a well casing, the electric submersible pump comprising:
 an electric motor; 
 a centrifugal pump driven by the electric motor when the electric motor is energized, wherein the centrifugal pump includes an intake manifold; 
 a gas mitigation system comprising:
 a canister having an interior; and 
 an intake screen; 
 
 a bottom intake pipe, wherein the bottom intake pipe extends from the interior of the canister to the intake manifold of the centrifugal pump; and 
 a screen flush module, wherein the screen flush module comprises:
 a flush diverter connected to the tubing string above the centrifugal pump; 
 a wash line extending from the flush diverter to the bottom intake pipe through the intake manifold of the centrifugal pump; and 
 wherein the flush diverter is configured to release fluids under hydrostatic pressure within the tubing string above the centrifugal pump into the gas mitigation system to selectively backwash particles trapped by the intake screen of the gas mitigation system. 
 
 
     
     
       2. The pump of  claim 1 , wherein the gas mitigation system further includes a flush manifold that has a plurality of nozzles within the canister. 
     
     
       3. The pump of  claim 1 , wherein the screen flush module is configured to be automatically placed into a flush mode of operation by the hydrostatic pressure of fluid in the tubing string when the electric motor is not energized. 
     
     
       4. The pump of  claim 3 , wherein the flush diverter comprises:
 a flush discharge; and 
 a shuttle valve that selectively opens the flush discharge to permit pressurized fluid to pass from the tubing string through the flush diverter and into the wash line during the flush mode of operation. 
 
     
     
       5. The pump of  claim 4 , wherein the shuttle valve comprises:
 a shuttle cage; 
 a check ball contained within the shuttle cage; 
 a seat; and 
 a spring that biases the shuttle cage in an open position in which the check ball is displaced from the seat. 
 
     
     
       6. The pump of  claim 5 , wherein the shuttle valve is configured such that the shuttle cage blocks the flush discharge when the shuttle valve is urged to the open position. 
     
     
       7. The electric submersible pump of  claim 1 , wherein the screen flush module further comprises a check valve within the intake manifold that closes the intake manifold of the centrifugal pump when the wash line contains pressurized fluid. 
     
     
       8. A pump configured to lift fluids through a tubing string contained in a well having a well casing, the pump comprising:
 an electric motor; 
 a centrifugal pump driven by the electric motor when the electric motor is energized; 
 a gas mitigation system comprising:
 a canister having an interior and an intake screen; and 
 an intake tube, wherein the intake tube extends from inside the canister to the centrifugal pump; and 
 
 a screen flush module, wherein the screen flush module comprises:
 a dump valve above the canister of the gas mitigation system; 
 an inlet line, wherein the inlet line connects the tubing string to the dump valve; 
 an outlet line, wherein the outlet line connects the dump valve to the intake tube below the centrifugal pump; and 
 wherein the dump valve is configured to release fluids under hydrostatic pressure within the inlet line and tubing string above the dump valve into the gas mitigation system through the outlet line to selectively backwash particles trapped by the intake screen of the gas mitigation system. 
 
 
     
     
       9. The pump of  claim 8 , wherein the dump valve comprises:
 a central passage; 
 a ball valve seat within the central passage; 
 a ball valve; and 
 an actuator to selectively lift the ball valve off the ball valve seat to permit fluid flow through the central passage, wherein the actuator includes a hydraulically-driven ram that is connected to the ball valve. 
 
     
     
       10. A pump configured to lift fluid through a tubing string contained in a well having a well casing, the pump comprising:
 an electric motor; 
 a centrifugal pump driven by the electric motor when the electric motor is energized; 
 a gas mitigation system comprising:
 a canister having an interior; and 
 an intake screen; 
 
 a bottom intake pipe, wherein the bottom intake pipe extends from the interior of the canister to the centrifugal pump; and 
 a screen flush module configured to selectively backwash particles trapped by the intake screen of the gas mitigation system, wherein the screen flush module comprises:
 a wash line connected to the gas mitigation system; and 
 a flush diverter connected to the tubing string, wherein the flush diverter comprises:
 a flush discharge; and 
 a shuttle valve that selectively opens the flush discharge to permit pressurized fluid to pass through the wash line into the interior of the canister during the flush mode of operation; and; 
 
 wherein the screen flush module is configured to be automatically placed into a flush mode of operation by a hydrostatic pressure of the fluid in the tubing string when the electric motor is not energized. 
 
 
     
     
       11. The pump of  claim 10 , wherein the shuttle valve comprises:
 a shuttle cage; 
 a check ball contained within the shuttle cage; 
 a seat; 
 a spring that biases the shuttle cage in an open position in which the check ball is displaced from the seat; and 
 wherein the shuttle valve is configured such that the shuttle cage blocks the flush discharge when the shuttle valve is urged to the open position while the electric motor is energized. 
 
     
     
       12. The electric submersible pump of  claim 10 , wherein the screen flush module further comprises a check valve within the intake manifold that closes the intake manifold of the centrifugal pump when the wash line contains pressurized fluid.